Prior to diagnosis it seemed like I got 3 colds a year, every year. In high school though I was constantly sick... a new cold virus every month with bad tonsils that eventually needed to come out. A bit more sick than average... and the true flu a couple of times in my 20s but otherwise healthy not needing antibiotics, etc. I did get a kidney infection too just prior to getting lupus diagnosis.
After diagnosis - for a while - it seemed like I got sick *less* often, and since being around young children especially I've been getting sick constantly again with multiple stomach bugs, colds, sinus infections, eye infections, etc. It's been a crazy nearly 4 years now... in the process I did discover that I am IgA deficient, and that is probably part of the reason I tend to catch everything! IgA deficiency is also linked to a higher likllihood of developing lupus or autoimmune illness too. Something like this could be a possibility for you too, but there's not much treatment for it really. For me, it's just "interesting" to know.
The only suggestion I have for you is to wash your hands more and avoid touching your nose/eyes and mouth like the plague.
Otherwise from your post you're already doing everything right!